3-d mapping for guidance of device advancement out of a guide catheter

ABSTRACT

The present disclosure involves a process for guiding the distal end of a guide wire or working catheter as it emerges from the distal end of a guide catheter into a blood vessel. The distal end of the guide wire or working catheter is provided with an X-ray marker, a determination is made that this distal end has emerged from the distal end of the guide catheter and a fluoroscopic image of the distal end of a guide wire or working catheter is taken. This image is correlated with the length of guide wire or working catheter inserted into the guide catheter. After further advancement of the guide wire or working catheter, another fluoroscopic image of the distal end of a guide wire or working catheter is taken and this image is correlated with the length of guide wire or working catheter which has been inserted into the guide catheter.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Non-Provisional of U.S. Provisional ApplicationNo. 61/839,459, filed Jun. 26, 2013, entitled “ROBOTIC IMAGE CONTROLSYSTEM”, of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Systems exist for the robotic feeding of percutaneous interventionaldevices such as guide wires and working catheters into guide catheters.The guide catheters are typically placed by manual manipulation ofmedical personnel such that their distal ends are adjacent to the siteof action for the intervention, typically a valve or chamber of theheart or a lesion in a blood vessel such as an artery. In the case ofcoronary arteries the guide catheter may be placed adjacent to theentrance of the artery into the aorta. The interventional devices suchas guide wires and working catheters may be fed by the operation ofrobotic controls by medical personnel such as shown in U.S. Pat. No.7,887,549. The working catheters may be equipped with balloons, stentsor stents enclosing balloons. The path of a guide wire or workingcatheter as it emerges from the distal end of a guide catheter shouldfollow the lumen of the blood vessel into which it is being inserted andthis path may not lie in a single 2-D plane. Guiding the advancement ofsuch a device with a fluoroscopic image that typically lies in a planethus presents some challenges.

SUMMARY OF THE INVENTION

The present invention involves a process for guiding the distal end of aguide wire or working catheter as it emerges from the distal end of aguide catheter into a blood vessel. The distal end of the guide wire orworking catheter is provided with an X-ray marker, a determination ismade that this distal end has emerged from the distal end of the guidecatheter and a fluoroscopic image of the distal end of a guide wire orworking catheter is taken. This image is then correlated with the lengthof guide wire or working catheter that has been inserted into the guidecatheter. After further advancement of the guide wire or workingcatheter, another fluoroscopic image of the distal end of a guide wireor working catheter is taken and this image is correlated with thelength of guide wire or working catheter which has been inserted intothe guide catheter. This information is used to guide the furtheradvancement of guide wire or working catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

This application will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements inwhich:

FIG. 1 is a schematic of the environment in which percutaneousinterventional procedures are robotically performed.

FIG. 2 is a schematic of the placement of a guide catheter and a guidewire in a human body.

FIG. 3 is a schematic of a guide catheter in relationship to the planeof a 2-D fluoroscopic image.

FIG. 4 is a flow diagram of creating a 3-D map of the path of a guidewire emerging from a guide catheter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the environment in which the various embodiments ofthe present invention find particular utility involves a catheterlaboratory 10 for robotically performing percutaneous interventionalprocedures. A patient 11 is supported on a table 14 and the procedure isobserved with fluoroscopic X-ray equipment 12. A cassette 22 supportedby a robotic arm 20 which is used to automatically feed a guide wire 50(shown in FIG. 2) into a guide catheter 40 seated in an artery of thepatient 11. The cassette 22 is controlled from a remote station 24 inorder to isolate the medical personnel conducting the procedure fromexposure to the X-ray radiation used to monitor the procedure by use offluoroscopic equipment. The station includes remote controls 26 forcontrolling the cassette 22 and a screen 28 with which to monitor theprogress of the procedure. It displays the arterial system 29 beingaddressed by the procedure. U.S. Pat. No. 7,887,549, incorporated hereinby reference, has a detailed disclosure of this environment.

Referring to FIG. 2, a guide catheter 40 that has been fed into thetorso 30 of a patient 11 to reach the cardiac region 32. Within theguide catheter 40 is a guide wire 50 whose tip 52 has not yet passed outof the distal end 42 of the guide catheter 40. The X-ray equipment whichis used to monitor the progress of the guide wire 50 as it passesthrough the guide catheter 40 and approaches its distal terminus 42 maybe controlled such that it images the entire path until the guide wiretip enters the cardiac region 32 and then just images the cardiac region32. It may also be controlled to take images at a more frequent rateonce the tip 52 enters the region 32.

Referring to FIG. 3, a guide catheter 40 follows the path of an arterythat is not illustrated. It has a portion 47 that has passed below theplane 90 of the fluoroscopic image into a lower plane 94 and it has aportion 49 that has passed above the plane 90 into a higher plane 92.Iterative fluoroscopic images in plane 90 can be combined withmeasurements of the length of guide wire being fed into the guidecatheter to yield an indication of the 3-D path of the guide catheterand therefore the artery itself.

Referring to FIG. 4, a step-by-step procedure may be followed to developthe indication of the 3-D path of a guide wire or working catheter as itemerges from the distal end of a guide catheter from iterativefluoroscopic images.

One embodiment involves using the Pythagorean Theorem to estimate thelocation of the tip of a guide wire in three dimensional space. Theapparent length of the guide wire distal portion in a fluoroscopic imageis taken as one leg, the length of guide wire involved in the image istaken as the hypotenuse and the height out of the plane is taken as theother leg of a right triangle. Basic trigonometry allows a calculationof the angle of the hypotenuse out of the plane of the image.

One embodiment involves taking fluoroscopic images repeatedly andperforming correlations repeatedly during the further advancement of theguide wire or working catheter. Each correlation may be used to guidethe advancement of the guide wire or working catheter from the point ofthat correlation.

One embodiment involves determining the emergence of the distal end ofthe guide wire or working catheter using an X-ray marker on the guidecatheter and a fluoroscopic image that includes this marker and thedistal end of the guide catheter. This X-ray marker may be located closeenough to the distal end of the guide catheter that any movement of theguide wire or working catheter the out of plane of this fluoroscopicimage can be ignored in making the determination without creating asignificant error. One embodiment involves measuring the length of guidewire or working catheter fed to the guide catheter after the distal endof the guide wire or working catheter is detected at this X-ray markerand this measurement is used to determine the emergence.

One embodiment involves using the foreshortening in the fluoroscopicimages to estimate the path of the blood vessel extending from thedistal end of the guide catheter to the ultimate destination of thedistal end of the guide wire or working catheter.

One embodiment involves using image-processing software to determinewhen the distal end of the guide wire or working catheter has emergedfrom the guide catheter. This software may also be involved incontrolling the taking of fluoroscopic images and the correlations ofthese images with the length of guide wire or working catheter fed tothe guide catheter.

One embodiment involves using the information obtained from determiningthe position in three dimensional space of the distal end of a guidewire or working catheter to align the plane of a 2-D fluoroscopic imageapproximately tangent to the path of its further advancement. Multiple2-D fluoroscopic images may be used to determine a series of tangents tothe blood vessel along the path of further advancement and the X-rayequipment is adjusted to provide a 2-D fluoroscopic image whose plane isapproximately tangent to a portion of the path of further advancementyet to be traversed. One embodiment involves taking the 2-D fluoroscopicimages with X-ray equipment mounted on a C-arm and rotating the C-arm isto align the plane.

One embodiment involves taking fluoroscopic images at frequent enoughintervals after the distal end of a guide wire or working catheter hasemerged from the distal end of the guide catheter that any change frommoving away from to moving toward the plane of the 2-D fluoroscopicimages may be readily detected.

One embodiment involves fitting the discrepancies between the actuallength fed of a guide wire or working catheter and the apparent travelafter emergence from the distal end of the guide catheter in thefluoroscopic images to an anatomical model. The precisethree-dimensional path of any given blood vessel may be unique to thatblood vessel and to the person in whom that blood vessel resides butblood vessels of a certain type generally follow a certain generalizedpath. For instance the right coronary artery (RCA) follows the samegeneralized path away from the ascending aorta despite differences fromindividual to individual.

One embodiment involves taking multiple fluoroscopic images at a givenpoint in the progression of the guide wire or working catheter out ofthe distal end of the guide catheter. The images at a given point lie indifferent planes. This facilitates determining the position of thedistal end of the guide wire or working catheter in three-dimensionalspace at that point in its progression.

One embodiment involves using standard comparison techniques onsuccessive fluoroscopic images. Successive images may be aligned using afeature or “reference point” expected to be invariant between the imagesbeing compared. Alternatively a shift or a shift and rotation within thefluoroscopic plane may be calculated to cause the second image tocorrespond to the first with a high degree of correlation. One image maybe selected as a reference or “gold standard” image and all other imagescompared to it or two successive images may just be compared to eachother. If the two images as a whole cannot be matched with a high degreeof correlation, the effective area of interest can be minimized tocontain just the information needed to follow the distal end of theguide wire or working catheter. Successive images may be timed so thatthey both occur at the same point in the patient's cardiac or breathingcycle or both. The aim is to minimize any difference between the imagesthat is not related to the progression or travel of the guide wire orworking catheter.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered presently to be thebest mode thereof, those of ordinary skill will understand andappreciate the existence of variations, combinations, and equivalents ofthe specific embodiment, method, and examples herein. The inventionshould therefore not be limited by the above described embodiment,method, and examples, but by all embodiments and methods within thescope and spirit of the invention as claimed.

What is claimed is:
 1. A process for guiding the distal end of a guide wire or working catheter as it emerges from the distal end of a guide catheter residing in a blood vessel comprising; providing the distal end of the guide wire or working catheter with an X-ray marker; determining that this distal end has emerged from the distal end of the guide catheter; taking a fluoroscopic image of the distal end of a guide wire or working catheter; correlating this image with the length of guide wire or working catheter which has been inserted into the guide catheter; after further advancement of the guide wire or working catheter, taking another fluoroscopic image of the distal end of a guide wire or working catheter and correlating this image with the length of guide wire or working catheter which has been inserted into the guide catheter; using this information to guide the further advancement of guide wire or working catheter.
 2. The process of claim 1 wherein fluoroscopic images are taken repeatedly and correlations are performed repeatedly during the further advancement of the guide wire or working catheter.
 3. The process of claim 2 wherein each correlation is used to guide the advancement of the guide wire or working catheter from the point of that correlation.
 4. The process of claim 1 wherein the emergence of the distal end of the guide wire or working catheter is determined using an X-ray marker on the guide catheter and a fluoroscopic image that includes this marker and the distal end of the guide catheter.
 5. The process of claim 4 wherein this X-ray marker is located close enough to the distal end of the guide catheter that any movement of the guide wire or working catheter the out of plane of this fluoroscopic image can be ignored in making the determination.
 6. The process of claim 1 wherein the emergence of the distal end of the guide wire or working catheter is determined using an X-ray marker on the guide catheter.
 7. The process of claim 6 wherein the length of guide wire or working catheter fed to the guide catheter after the distal end of the guide wire or working catheter is detected at this X-ray marker is measured and this measurement is used to determine the emergence.
 8. The process of claim 1 wherein the foreshortening in the fluoroscopic images is used to estimate the path of the blood vessel extending from the distal end of the guide catheter to the ultimate destination of the distal end of the guide wire or working catheter.
 9. The process of claim 1 wherein the ultimate destination is a valve or chamber of a human heart or a lesion in a human blood vessel.
 10. The process of claim 1 wherein the emergence is determined with image processing software.
 11. The process of claim 1 wherein the information is used to align the plane of a 2-D fluoroscopic image approximately tangent to the path of further advancement.
 12. The process of claim 11 wherein multiple 2-D fluoroscopic images are used to determine a series of tangents to the blood vessel along the path of further advancement and the X-ray equipment is adjusted to provide a 2-D fluoroscopic image whose plane is approximately tangent to a portion of the path of further advancement yet to be traversed.
 13. The process of claim 12 wherein the X-ray equipment generating the 2-D fluoroscopic images is mounted on a C-arm and the C-arm is rotated to align the plane.
 14. The process of claim 11 wherein the images are taken as the guide wire or the working catheter is advanced and the time interval between successive images is short enough that any change from moving away from to moving toward the plane of the 2-D fluoroscopic images may be readily detected.
 15. The process of claim 2 wherein the discrepancies between the actual length fed and the apparent travel in the fluoroscopic images are fitted to an anatomical model.
 16. The process of claim 1 wherein fluoroscopic images in more than one plane are used.
 17. The process of claim 1 wherein successive images are compared using a common reference point appearing in all the images.
 18. The process of claim 1 wherein successive images are compared using a common subregion of the image appearing in all the images.
 19. The process of claim 2 wherein the timing of the successive images is such that cardiac motion is normalized. 